atomic weight

noun

: the mass of one atom of an element
specifically : the average mass of an atom of an element as it occurs in nature that is expressed in atomic mass units see Chemical Elements Table

Examples of atomic weight in a Sentence

Recent Examples on the Web That number is the atomic weight—the total number of protons and neutrons in the nucleus of the atom. Rhett Allain, WIRED, 23 Feb. 2024 Hydrogen was the focus of the earlier work because its low atomic weight influences the behavior of vibrations within the material in a way that promotes the formation of superconducting pairs of electrons. John Timmer, Ars Technica, 4 Aug. 2023 Also in the 1860s, the English chemist John Newlands became the first to order the elements according to atomic weight — a strategy that Mendeleev and others followed until the early 1900s, when the discovery of atomic numbers presented a more precise measure. Cody Cottier, Discover Magazine, 12 Apr. 2022 The second is the atomic weight. Andrew Moseman, Discover Magazine, 18 Dec. 2010 Many periodic tables include the atomic number (number of protons) and atomic weight (which depends on protons and neutrons). Bill Andrews, Discover Magazine, 26 June 2019 Specific trends, such as melting point and atomic radius, recur periodically among the elements when they’re listed in order of increasing atomic weight. Bill Andrews, Discover Magazine, 26 June 2019 Lead, with its heavy atomic weight, interferes with all of this as it gets swapped in for blood cells, neurons, and other crucial bits of biology. Michael J. Coren, Quartz, 16 June 2022 Plain ol’ carbon — carbon that has 6 protons and 6 neutrons for an atomic weight of 12 — is far more stable than radiocarbon, and therefore vastly more plentiful in Earth’s atmosphere. Rebecca Coffey, Forbes, 3 Mar. 2021

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'atomic weight.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1819, in the meaning defined above

Time Traveler
The first known use of atomic weight was in 1819

Dictionary Entries Near atomic weight

Cite this Entry

“Atomic weight.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/atomic%20weight. Accessed 20 Jun. 2024.

Kids Definition

atomic weight

noun
: the average atomic mass of an element compared to ¹⁄₁₂ the mass of the most abundant kind of carbon

Medical Definition

atomic weight

noun
: the mass of one atom of an element
specifically : the average mass of an atom of an element as it occurs in nature that is expressed in atomic mass units see Chemical Elements Table

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